The present invention relates to an apparatus that warns a driver of the abnormal tire inflation pressure. More specifically, the present invention pertains to a casing of a transmitter that is installed inside a tire for transmitting information concerning tire inflation pressure to a receiver in the vehicle.
A decrease of tire pressure lowers the performance of a vehicle. Therefore, drivers should be aware of an improper tire inflation pressure and take proper measures. Therefore, apparatuses for detecting the improper tire inflation pressure and warning the drivers have been suggested.
As shown in FIGS. 8 and 9, a prior art warning apparatus includes a transmitter 105 that transmits tire inflation pressure information to a receiver (not shown) in a vehicle. The transmitter 105 includes a box-shaped casing 103 and a valve stem 104 formed integrally on the casing 103. The casing 103 accommodates a pressure detector, a signal processing circuit, an electronic substrate, and a battery (not shown). An air hole 106 is formed in the casing 103. As shown in FIG. 9, the transmitter 105 is attached to a predetermined part of a wheel 12 such that the casing 103 is located inside a tire 9. Air is injected into the tire 9 from the valve stem 104 through the air hole 106. The valve stem 104 functions as an antenna for transmitting tire inflation pressure information.
FIG. 3 is a perspective view of a typical tire detaching apparatus 11. The tire detaching apparatus 11 includes a turn table having fixed hooks 14 and a roller 13, which is located above the turntable 15. The wheel 12 is fixed on the turntable 15 by the fixed hooks 14 and is rotated. In this state, the roller 13 is used to remove the tire 9 from the wheel 12.
As shown in FIG. 3, when the tire 9 is detached from the wheel 12, the roller 13 engages and pulls up a lower bead 9b of the tire 9 while the wheel 12 is rotated. However, as shown in FIGS. 8 and 9, the casing 103 of the prior art transmitter 105 has a peripheral wall 103a, which is perpendicular to the upper and lower surfaces of the casing 103. Accordingly, as shown by a broken line of FIG. 9, the lower bead 9b can contact the peripheral wall 103a when pulled up by the roller 13. This hinders the removal of the tire 9 and may damage the casing 103.